1. Field of the Invention
The present invention relates to a storage system, and more particularly to a change in the allocation of a real storage area to a virtual volume in a storage system having a virtualization apparatus of a redundant configuration.
2. Description of the Prior Arts
In the so-called SAN (Storage Area Network), a system that sets a plurality of virtual volumes with reference to the storage area of a storage device and uses their volumes from a host processor via a network is known.
Regarding a storage virtualization apparatus that virtualizes the storage device connected through the network and enables input-output (I/O) from the host processor, for example, there is such a system as disclosed in Japanese Unexamined Patent Application Publication No. Hei 2000-242434 (Patent Reference 1). According to this art, a storage device to which a virtual storage area provided to a host is allocated is changed by installing switching equipment 20 between a storage device system 1 and a host 30 and the switching equipment 20 changes the virtualization setting of a virtual storage device system provided to the host 30, thereby to change the storage device to which a virtual storage area to be provided to a host is allocated.
The configuration information about the storage virtualization apparatus (for example, array disk switch) group described in Patent Reference 1 is managed independently for each storage virtualization apparatus.
In such a storage virtualization system, the modification of the configuration information during system operation changes the destination during input-output processing and causes data corruption and an input-output fault. Accordingly, a method for reducing the storage virtualization apparatuses that operate concurrently during a configuration change to only one apparatus can be considered, but a problem that concentration of a load or fault tolerance decreases is arisen. The aforementioned Patent Reference 1 does not refer to the modification of configuration information indicating that one volume shifts to another volume while the storage device system is operating.